I had used keybase successfully on my Mac. After some time, I went to track someone and got this error:
error: `gpg` exited with code 2
warn: gpg: error reading key: Legacy key
I had no luck googling for answers, but a @mtigas suggested that I try
gpg2 --list-secret-keys
That revealed a very old dsa1024 key I had installed (expired in 2005). I tried
gpg2 --delete-secret-keys 998573AB
but it failed with
gpg: 998573AB: delete key failed: No pinentry
I was able to use Mac OS GPGTools to delete the key, and after that, regular keybase commands worked.
Hopefully this will help someone else with the same problem...